For the local irradiation of tumors, use is made of hollow needles to be introduced into the body, which needles are closed at one end and connect to a guide tube by their other end. A source of radiation with predetermined properties, such as the intensity, is attached to one end of a cable and, by means of that cable, can be brought from a shielded container via the guide tube into a predetermined position in the hollow needle and from that position back again into the shielded container. The displacement of a cable having a source of radiation at its one end is typically effected by connecting the other end of that cable to a drive unit which imposes a displacement on the cable such that the cable end with the radiation source is displaced through the guide tube into the needle. To that end, the other end can be coupled to a rotary drum, the cable end with the source of radiation being displaced by winding the cable onto the drum or unwinding it therefrom. The coupling of the other cable end to the drive unit is typically effected by locking the other cable end with locking means.
Often, a tumor is irradiated from more than one side and, accordingly, a plurality of needles may be present and optionally different sources of radiation may be present in the different needles. In this connection, it is of great importance that the proper source of radiation with the desired intensity and form ends up at a predetermined site. This requires close attention on the part of the operating staff. Choosing and mounting the correct source of radiation is naturally of equally great importance if only one needle and one source of radiation are used.
The object of the invention is to provide a guarantee, when working with such equipment, that the source of radiation coupled with a drive unit by means of a cable is in fact the intended source of radiation.